The goal of this project is to determine the mechanisms of lymphocyte mediated cutaneous pathology in allergic contact dermatitis to urushiol (Toxicodendron radicans, "poison ivy") and in drug eruptions. These conditions were chosen because the relevant antigen is known, lending them amenable to analysis. Both these conditions are a significant source of morbidity and economic loss. Allergic contact dermatitis is a leading cause of occupational disability and drug eruptions are a major source of morbidity in hospitalized patients. Lymphocyte function will be studied by the generation of IL2- dependent T-cell lines and clones from both peripheral blood and lesional skin of appropriate patients at various stages of their condition. Cultured T-cells will then be analyzed for phenotype, antigen specificity and function in a variety of in vitro assays. These techniques should reveal both the mechanisms of lymphocyte mediated pathology as well as its regulation. When applied to drug eruptions, these studies should be able to determine the relative role of drug (hapten) specific T-cells versus drug induced autoreactivity in the pathogenesis of this condition. It is hoped that these studies will lay the groundwork for future study of T-lymphocyte mediated conditions in which the inciting antigen is not known, such as sarcoidosis, lichen planus, and scleroderma.